Sound reproducer



Feb. 25, 1941. M. COMPARE SOUND REPRODUCER Filed Jan. 18, 1940 3 Sheets-Sheet 1 Feb. 25, 1941. u. COMPARE SOUND REPRQDUOBR med Jan. 18, 1940 3 Shasta-Shoot 2 M W w 0 w .w 0 n J r a .H I HF I ll. i JR Ill I: l u

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Feb. 25, 1941.

M. coMPARE 2.233.244

somm VREPRODUCER Filed Jun. 18, 1940 3 Shuts-Shed 3 Patented Feb. 25, 1941 UNITED STATES SOUND REPRODUCER Manrico Compare, Milan, Italy Application January 18, 1940, Serial No. 314,540 In Great Britain January 13, 1939 8 Claims.

, This invention relates to sound reproducers and loud speakers; I

The manufacture of sound reproducers is nowgenerally direc'tedto the production of cone type electromagnetic or electrodynamic loud speakers, as thesehavebeen found to be preferable to other types. The cone type speaker, however, still presents severaldrawbacks as, for example, the necessity of associating with it a screen or baflle, 10 without which the sound would 'be' distorted to such "an extent as to render the reproduction muffied and most disagreeable. The baffle has the function of separating the air pressure variations at the front of the cone from those at the back thereof and vice'versaflythen the cone vibrates.

An efiicient baffle should be calculated according to the acousticgamma of wave length, but a baflle actually complying with theory would be too large for practical use. In actual practice the size of the baffle isvery much reduced in order to render feasible its application to commercial sound reproducers and radio receivers. This reduction of size is therefore a compromise between the fidelity of sound and speech reproduction and 5 the practical size ,of baflle'. Further a good cabinet for a sound reproducer'cannot be designed without consideration of the loud speaker for which the cabinet itself must function as a. baflie. The cone type speaker is also undesirable as it projects sound in one direction only, whereas radiation or circular propagation is desired in many instances.

'. It is an object of the presentinvention to provide a new loud speaker which will overcome the above mentioned difliculties by comprising a mechanically practical unit which will produce better results. In conformation, this loud speaker may comprise a spheroidal or curviform structure adapted to vibrate at sound frequencies and to i 0 assume a swelling and subsiding at each vibration, the outer surface of which radiates sound in all directions. I The air contained within the spheroid sections has no communication with the outer air, hence the-elimination'of a baille or screen'as employed in the'present daycabinet;

Accordingly, the invention .broadly comprises a soundreprodu'cer substantially spheroidal in con-J's formation and combined with sound modifying means. One form of this arrangement is characterized by adjacent curviform diaphragms, such as spheres, spheroids or sections of same, one of I which has the function of producing and emitting I sound waves and the other the function of making said diaphragm aperiodic.

One of the features of the presentinvention comprises the positioning of elements within the vibratory structure, which elements have the function of making the same perfectly aperiodic.

The elasticity of the air contained inside the spheroid or sections of it, while allowing the '5 structure itself to expand and contract freely at all acoustical frequencies, also acts as a resilience to cause resonance atcertain frequencies. It is therefore desirable to incorporate the damping elements which may consist of spongy materials, 10 labyrinths or other elements. The vibratory spheroid may be actuated by a moving coil, a moving armature, or by a piezo-electric system. The spherical speaker canbe located'in'a" recess of a cabinet or separated from'it at will without 15 losing its acoustical characteristics. If the speaker is located in a'parabolic recess, its position can be adjusted to give the desired diverging angle of soundpropagation. i

A constructional arrangement of a spheroidal 20 sound reproducer may comprise a number of segments forming corrugations or indentations which extend from the-top to the bottom, the upper ends being held by screws to one end of a rod-likemember. "The dampers within the sphere 25 are preferably formed of spongy discs and are supported by said rod-like member. The lower part of the sphere may be free to move with a moving coil which, for instance, is actuated by an incoming variable electric current which 30 causes the expanding and contracting facilitated by the corrugations: Itinay also be arranged so that both polar ends of the vibrating structure are actuated simultaneously, thus, producing a moreeflicient and balanced system of sound re- 3 producer. If the materialof the structure is sufficiently elastic, the corrugations may be 'dispensed with. The moving coil with its core and spider support maybe secured in any known manner; 7

Alternatively, a damper may comprise a spheroid shaped member placed withinthe sound reproducer, the two spheres being attached at their polar ends and having a space between their substantially concentric walls. .The damper sphere 4 is-providedwith a largenumber of perforations which permits air to flow therethroughwith a resistance and thereby produce a-damping effect.

Thespheroidal reproducer may be actuated piezoelectrically bymeans of a suitablepiezo-eiectric 5 substance placed between the two diaphragms and which may be applied as a coating or covering on the outside of the perforated internal sphere or tothe inner surface of the external vibrating sphere, The vibration of the sphere will thereby be effected through the intervening dielectric. A step-up transformer would be employed in this arrangement, the primary of which is connected to the source of current and the ends of the secondary to the piezo-electric diaphragm and the other diaphragm respectively, both diaphragms being formed of conductive material.

The invention both as to its organization and method of operation, together with additional objects and advantages, will best be understood from the following description of the specific embodiments when read in connection with the accompanying drawings, wherein like reference characters indicate like parts throughout:

Figure 1 is a view in elevation of a spheroidal sound reproducer embodying the present invention;

Figure 2 is a plan view of the member shown in Figure 1; and

Figures 3, 4, 5 and 6 are views in elevation of spheroidal sound reproducers embodying modifications of the present invention, portions of Figures 5 and 6 being broken away to show the interior structure thereof.

With specific reference to the drawings, Figure 1 shows a spheroid It, the upper part or pole of which is fixed by a cap I! and a screw II to a supporting rod H. The lower part or pole of the spheroid II is free to move and is fixed to a spider l5. corrugations ll extend longitudinally about said spheroid l from'its poles The spider I is mounted upon a moving coil I which causes the expanding and contracting or vibrating of the spheroid III as indicated by the broken lines. This vibration is permitted and/or facilitated by the corrugations II as best shown in Figure 2. The moving coil l6 comprises a part of an electmmagnet 23 and is mounted on a core l1 and connected with a source of electric energy by the leads l8 and It. The coil structure is contained within a support I! to which the supporting rod I4 is fixed by a threaded extension 2. and a nut 2|. Damping members 22, in the form of spo y discs, are positloned within the spheroid III and supported by the rod l4.

The various elements of the structure may be changed to suit variable conditions as shown in Figure 3 wherein a semi-spheroidal sound reproducer II is provided with spiral corrugations ll extending over the surface of. the sphere and betweeen its poles. In addition, the electromagnet ll comprising the moving coil I! may be D sitloned within the sphere and secured to the inner end of the supporting rod ll. Sound modifying means Il may be positioned between the rod l4 and the electromagnet 23. The exterior end of the rod It may be secured to one pole of the spheroidal structure by a cap I! and a screw I3, and the electromagnet may be secured to a collar 25 which-is fixed about the other pole of the spheroid.

The core I! of the electromagnet 23 may extend through the collar II and be fixed to any suitable supporting means. According to this arrangement the moving coil of the electromagnet N, in responding to electric impulses, will move reciprocally back and forth upon the core l1 and cause the poles of the spheroid to expond and contract. The vibration of the poles i n this manner will cause the entire surface of the spheroid to vibrate accordingly and the spiral corrugations will cause a spiral movement of the wall of the sphere II. It will be seenby the drawing that the motivating means is positioned substantially within the sphereand that the two poles will be simultaneously actuated.

Another form of sound modifying means may be associated with the sphere as best shown in Figure 4. According to this structure the sphere and electromagnet may be arranged as heretofore described but the sound modifying means comprises a series of parallel ballie plates 26 circumventing the exterior of the spheroidal structure Ill. These baflie plates 28 may extend radially with respect to the supporting rod I4 and be provided with openings 21 conforming to the formation of the wall of the spheroid ill, and arranged so that the edges of said openings 2! lie closely adjacent to the surface of said wall. The baille plates 26 may be mounted in any suitable manner as upon rods 28 supported by brackets 29 which may be secured to the housing of the electromagnet 23. These baiiles lt'may be of any suitable form or shape but of course the openings must be concentric with respect to the wall of the spheroid II so that they may function to compensate the low sound frequencies as is well known.

The damping means may assume various forms and comprise various materials. As shown in Figures 5 and 6, for instance, a second spheroid 3|] may be positioned within'the sound reproducing spheroid Hi. This spheroid is provided with perforations ii to permit the air to pass in and out of the interior chamber and the exterior space between the two sphere walls. The passing of the air through the perforations 3i creates a resistance to the free flowing of the air and thereby sets up a damping effect. If a relatively rigid inner sphere 30 is employed the outer sphere may be mounted directly upon it at their poles, as shown in Figure 5, the screw I! being secured to the inner spheroid 30 at one pole and the vibrating means being secured to said inner spheroid 30 at the opposite pole.

This type of structure also permits a modification in the vibrating means as shown in Figure6. Instead of employing an electromagnet for vibrating the sound reproducing sphere it may be actuated piezo-electrically. For instance, suitable ,piezo-electric material may be coated upon the inner wall of the spheroid II, the outer wall of the damping spheroid 30' or otherwise positioned upon or between the concentric walls in any suitable manner. A suitable method oicoating piezo-electric material is disclosed in German Patent 476,506 issued to Siemens and Halske Akt.-Ges. May 22, 1929. This would require that the two concentric spheres be formed of an electric conducting material. The primary of a suitable step-up transformer 32 may be connected to a source of current and the secondary to the spheres which form piezo-electric armatures. According to this arrangement the electric impulses will act upon the external vibrating sphere through the dielectric II.

The use of a piezo-electric activating means also permits structural modifications of the sound reproducer. For instance, a substantially spherical vibrating member ll may be employed and supported at only one pole. Likewise. the entire damping spheroid Il may also be substantially spherical and supported at only one pole. In other words, the two spheres may be supported at one point adjacent the transformer means and the whole surface of the sphere Il may thereby be employed to produce a vibrating effect as indicated by the broken lines.

Although'certain specific embodiments of the present invention have been shown and described, many modifications thereof are possible, and the present disclosure should be construed only in an illustrative sense. The present invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support at one point of said body, means connected with said body to cause the contraction and expansion thereof, and sound modifying means positioned within said body to modify the sound waves produced thereby.

2. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support at one point of said body, means connected with said body to cause the contraction and expansion thereof, a second hollow approximately spherical body positioned within said first mentioned body to modify the sound Waves produced thereby and having a plurality of apertures therein.

3. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support at one point or said body, a second hollow approximately spherical body positioned within said first mentioned body to modify the sound waves produced thereby having a plurality of apertures therein, the walls of said two bodies being sub stantially parallelly spaced and formed of electrically conducting materials, and a piezo-electric substance positioned between said walls to cause the contraction and expansion of the outer spherical body.

4. A sound reproducing device comprising in combination a hollow approximately spherical body, substantially the whole surface of which is adapted to be expanded and contracted to thereby produce sound waves, said body comprising a solid wall, a support at one point of said body, means connected with said body to cause the contraction and expansion thereof, and corrugations in said body to facilitate said expansion and contraction.

5. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support at one point of said body, operating means connected with said body to cause the contraction and expansion thereof, and corrugations in said body to facilitate said expansion and contraction, said corrugations extending longitudinally about said body from the point at which said operating means contacts said body.

6. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support at one point of said body, means connected with said body to cause the contraction and expansion thereof, said corrugations extending spirally about said body.

7. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support fixed at one point of said body and extendingtherethrough, means connected with said body to cause the contraction and expansion thereof, and sound modifying means positioned within said body to modify the sound waves produced thereby, said sound modifying means comprising a plurality of spaced discs mounted on said support.

8. A sound reproducing device comprising in combination a hollow approximately spherical body adapted to be expanded and contracted to thereby produce sound waves, a support at one point of said body, piezo-electric means connected with said body to cause the contraction and expansion thereof, and sound modifying means positioned within said body to modify the sound waves produced thereby.

' MANRICO COMPARE. 

